A conventional electrochromic film generally includes two electrochromic units, and an adhesive layer connected therebetween. The manufacturing of the electrochromic film begins with formation of the electrochromic units. One of the electrochromic units includes a substrate, a transparent electrically conductive layer, and an electrochromic layer laminated upon one another in that order. The other one of the electrochromic units includes a substrate, a transparent electrically conductive layer, and an ion storage layer laminated upon one another in that order. Then the adhesive layer is disposed and cured between the electrochromic layer and the ion storage layer of the electrochromic units. The resulting electrochromic film may be subjected to subsequent processes, such as cutting, electrode-forming, activating, cleaning, etc., so as to form the electrochromic film in flat form.
In usage, the electrochromic film is frequently attached to a curved substrate, such as a curved lens. For secure adhesion of the electrochromic film to the curved substrate, the electrochromic film is forcibly bent after curing by applying an external force so as to conform to the contour of the curved substrate. However, the aforementioned post-curing bending process cannot afford satisfying bonding strength between the electrochromic film and the curved substrate, and tends to generate relatively large inner stress of the electrochromic film, which results in separation of the two electrochromic units from each other.